Piston eob



Patented Urt'. 28,1919.

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PISTON FOR IN TEEN AL-COMBUSTION ENGINES.

Specincatlon of Letters Patent.

Patented Oct. 28, 1919.

ApplicationA tiled September 15, 1914, Serial No. 861,919. Renewed August 18, 1919. Serial Ho, 317,379.

To all whom it may concern I Be it known that I, Hnoo J UNKnRs a subject of the German Emperor, residing 'at Aachen, Germany, have invented certain new and useful Improvements in Pistons for Internal-Combustion Engines, of which the following is a specification.

This invention relates to pistons for internal combustion engines. The object of I0 the invention is to provide an improved construction for the piston of such an engline ed ture and whereby loss of heat due to the ca'rrying away o heat by the piston is greatly reduced.

In accordance with vide upon the end of plicity. of narrow grooves istributed over the end of the piston which is exposed to the combustible gases, there being preferably as many grooves as is ssible in order that the surface portion of e piston which is heated most severely 4can `expand freely and the grooves being very narrow so that very little heat will lbe conducted away therein. In some instances, when the construction is such that the end of the piston is subjected to greater heat over one part thereof than 3o over another, I find it desirable to provide a the invention, I prothe iston a multigreater number of grooves over that art of the piston which 1s most severely cated. In certain cases the grooves requireto be of only such a 'width that the individual parts boundin them can expand freely and ludependent y of one another. This may be a fraction of a millimeter. No current of gas which enters into such narrow grooves can eddy in them, so that no material losses of 40 heat can arise in the grooves. In addition, owing to therelatively' small width and great depth of the grooves they become filled with the residues of combustion when the engine is workin which residues exercise 451-2111 insulating action without preventing expansion. If desired, the grooves may be enlarged toward the interior of the piston so that the residues of combustion are prevented from falling out of them. Instead of employing the residues as insulation, the

grooves may be provided from the first with an insulating material or the insulating lneterial may be cast into the piston head.

As mentioned above, the grooves should be most numerous where the head of the piston is heated most highly by the fuel. For example, if the fuel 1s injected toward the midd e of the piston most rooves should be in the middle. On the ot er hand, if the fuel is injected parallel to the head of the piston, as is the case for example in twin piston engines in which the jet of fuel does not contact at all with the iston but spreads out during the combustion like a fan infront of the piston, in consequence of the approximately uniform heat over the surface of the piston, the grooves should be distributed over the end of the iston head. In the latter ease, however, t ere would be more of them at the edge of the piston nearest the place of injection than in the middle.

The grooves are preferably milled into the head o the piston when it is not possible to cast them owing to their small width. If desired, however, they may be made in any V other suitable way.

hese ends, the invention consists in the construction, arrangement and combination of parts described pointed out in the clalms. s

Several illustrative embodimentsA of the invention are represented by way of example in the accompanying drawing, w Figure 1 is a section of art of a piston head having grooves accor ing to the present invention,- Y

Fig. 2 shows a modified form of groove, Figs. 3 and 4 show grooves filled with 1nsulatlng material, Fig. 3 being a vertical section taken on the lihe 3 3 in Fig. 4, and 90 Fig. 4 a horizontal section on the line 4-4 in Fig. 3;

Fig. 5 is a vertical section showing part of a cylinder containing two pistons and how the grooves are preferably arranged when the fuel isinjected approxlmately parallel to the head of the piston, and

Fig. 6 is a like view showin the arrangement of the grooves when to fuel is 1nj'ected approximately at right-angles to the piston head.

Referring to these drawings, Fig. 1 shows a portion of a piston having a plurality of very narrow and relatively deep grooves 2 distributed over the surface 5 of the piston which comes into contact with'the combustible gases. In the construction shown in Fig. 2, the grooves enlarge toward the interior of the piston in order hereinafte that the residues of combustion which enter 110 of the portion with a single them and act as an insulator of heat cannot fall out.

Instead of the grooves being left to be filled with the residues of combustion they ma be filled from the beginning with insulation, but it must be possible for the material of the piston left between the -ves to expand In the "arrangement shown in Figs. 3 and 4 insulation 6 has been cast into the head of the piston and has the sha shown in plan view in Fig. 4 expansion of the piston head being possible owin t0 narrow aps extending to the layer o insulation. nstead of the insulation bein cast in when makin the piston, if desire it ina be introdu into the grooves after the piston has been cest.

In 5, a construction is shown consisting of a cylinder having two pistons therein adapted to reciprocate in opposite directions. The fuel is admitted to the space within the adjacent faces, the grooves h wells close together and be' k lel, as shown 1n Figs. 1, 3 an 5, or su antially parallel but .slilxtly wider at the bottom, as indicated in ig. 2; number of grooves is inc over the portion of. he .two pistons which, when the pistons@ ther, adjacent inlets. ig. 6 'shows a cylinder iston reciprocating erein and an inlet v' `ve in the end of the cylinder directed toward lthe end of the piston. The

contractlon with chang A grooves in the the head thereo thegrooves being referably the4 lie Aclosest to the p deep narrow grooves are provided in the end of the piston and these are preferably arranged closer together at the center.

1. A piston for an internal combustion engine constructed to permit expansion and es of temperature without injury by providing a pluralit of deep and narrow grooves on the end o the iston which is exposed to the fuel and aving said grooves shaped to reduce heat losses b making them so narrow as to substantialiy prevent movement of the gases of combustion in the grooves when the engine is in operation; substantially as described.

2. A piston for internal combustion en- 'nes having a plurality of ves in the end face of the head thereof, and a liner of insulation in each groove, the free s ace in each liner being very narrow and re atively deep.

3.1i piston for internal combustion engines having a plurality of very narrow p relatively deep grooves 1n the end face o the head thereof each groove being with insulation, for the purpose specified.

4. A piston for internal combustion en- 'nes having a plurality of very narrow relatively deep end face of located hat part of the piston closest tother at t head whic is exposed to the greatest heat,

for the purpose specified.

lIn testimon w ereof I aflix my signature in presence o two witn.

4 HUGO JUNKER-S. Witn:

Ltmwie Waonusnn., Hamelen Zimmerman. 

